2 * CPPC (Collaborative Processor Performance Control) driver for
3 * interfacing with the CPUfreq layer and governors. See
4 * cppc_acpi.c for CPPC specific methods.
6 * (C) Copyright 2014, 2015 Linaro Ltd.
7 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; version 2
15 #define pr_fmt(fmt) "CPPC Cpufreq:" fmt
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/delay.h>
20 #include <linux/cpu.h>
21 #include <linux/cpufreq.h>
22 #include <linux/dmi.h>
23 #include <linux/time.h>
24 #include <linux/vmalloc.h>
26 #include <asm/unaligned.h>
28 #include <acpi/cppc_acpi.h>
30 /* Minimum struct length needed for the DMI processor entry we want */
31 #define DMI_ENTRY_PROCESSOR_MIN_LENGTH 48
33 /* Offest in the DMI processor structure for the max frequency */
34 #define DMI_PROCESSOR_MAX_SPEED 0x14
37 * These structs contain information parsed from per CPU
38 * ACPI _CPC structures.
39 * e.g. For each CPU the highest, lowest supported
40 * performance capabilities, desired performance level
43 static struct cppc_cpudata **all_cpu_data;
45 /* Capture the max KHz from DMI */
46 static u64 cppc_dmi_max_khz;
48 /* Callback function used to retrieve the max frequency from DMI */
49 static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
51 const u8 *dmi_data = (const u8 *)dm;
52 u16 *mhz = (u16 *)private;
54 if (dm->type == DMI_ENTRY_PROCESSOR &&
55 dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
56 u16 val = (u16)get_unaligned((const u16 *)
57 (dmi_data + DMI_PROCESSOR_MAX_SPEED));
58 *mhz = val > *mhz ? val : *mhz;
62 /* Look up the max frequency in DMI */
63 static u64 cppc_get_dmi_max_khz(void)
67 dmi_walk(cppc_find_dmi_mhz, &mhz);
70 * Real stupid fallback value, just in case there is no
78 static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
79 unsigned int target_freq,
80 unsigned int relation)
82 struct cppc_cpudata *cpu;
83 struct cpufreq_freqs freqs;
87 cpu = all_cpu_data[policy->cpu];
89 desired_perf = (u64)target_freq * cpu->perf_caps.highest_perf / cppc_dmi_max_khz;
90 /* Return if it is exactly the same perf */
91 if (desired_perf == cpu->perf_ctrls.desired_perf)
94 cpu->perf_ctrls.desired_perf = desired_perf;
95 freqs.old = policy->cur;
96 freqs.new = target_freq;
98 cpufreq_freq_transition_begin(policy, &freqs);
99 ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
100 cpufreq_freq_transition_end(policy, &freqs, ret != 0);
103 pr_debug("Failed to set target on CPU:%d. ret:%d\n",
109 static int cppc_verify_policy(struct cpufreq_policy *policy)
111 cpufreq_verify_within_cpu_limits(policy);
115 static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
117 int cpu_num = policy->cpu;
118 struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
121 cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
123 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
125 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
126 cpu->perf_caps.lowest_perf, cpu_num, ret);
129 static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
131 struct cppc_cpudata *cpu;
132 unsigned int cpu_num = policy->cpu;
135 cpu = all_cpu_data[policy->cpu];
138 ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
141 pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
146 cppc_dmi_max_khz = cppc_get_dmi_max_khz();
149 * Set min to lowest nonlinear perf to avoid any efficiency penalty (see
150 * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
152 policy->min = cpu->perf_caps.lowest_nonlinear_perf * cppc_dmi_max_khz /
153 cpu->perf_caps.highest_perf;
154 policy->max = cppc_dmi_max_khz;
157 * Set cpuinfo.min_freq to Lowest to make the full range of performance
158 * available if userspace wants to use any perf between lowest & lowest
161 policy->cpuinfo.min_freq = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz /
162 cpu->perf_caps.highest_perf;
163 policy->cpuinfo.max_freq = cppc_dmi_max_khz;
165 policy->transition_delay_us = cppc_get_transition_latency(cpu_num) /
167 policy->shared_type = cpu->shared_type;
169 if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
172 cpumask_copy(policy->cpus, cpu->shared_cpu_map);
174 for_each_cpu(i, policy->cpus) {
175 if (unlikely(i == policy->cpu))
178 memcpy(&all_cpu_data[i]->perf_caps, &cpu->perf_caps,
179 sizeof(cpu->perf_caps));
181 } else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
182 /* Support only SW_ANY for now. */
183 pr_debug("Unsupported CPU co-ord type\n");
187 cpu->cur_policy = policy;
189 /* Set policy->cur to max now. The governors will adjust later. */
190 policy->cur = cppc_dmi_max_khz;
191 cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
193 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
195 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
196 cpu->perf_caps.highest_perf, cpu_num, ret);
201 static struct cpufreq_driver cppc_cpufreq_driver = {
202 .flags = CPUFREQ_CONST_LOOPS,
203 .verify = cppc_verify_policy,
204 .target = cppc_cpufreq_set_target,
205 .init = cppc_cpufreq_cpu_init,
206 .stop_cpu = cppc_cpufreq_stop_cpu,
207 .name = "cppc_cpufreq",
210 static int __init cppc_cpufreq_init(void)
213 struct cppc_cpudata *cpu;
218 all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);
222 for_each_possible_cpu(i) {
223 all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
224 if (!all_cpu_data[i])
227 cpu = all_cpu_data[i];
228 if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
232 ret = acpi_get_psd_map(all_cpu_data);
234 pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
238 ret = cpufreq_register_driver(&cppc_cpufreq_driver);
245 for_each_possible_cpu(i) {
246 cpu = all_cpu_data[i];
249 free_cpumask_var(cpu->shared_cpu_map);
257 static void __exit cppc_cpufreq_exit(void)
259 struct cppc_cpudata *cpu;
262 cpufreq_unregister_driver(&cppc_cpufreq_driver);
264 for_each_possible_cpu(i) {
265 cpu = all_cpu_data[i];
266 free_cpumask_var(cpu->shared_cpu_map);
273 module_exit(cppc_cpufreq_exit);
274 MODULE_AUTHOR("Ashwin Chaugule");
275 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
276 MODULE_LICENSE("GPL");
278 late_initcall(cppc_cpufreq_init);
280 static const struct acpi_device_id cppc_acpi_ids[] = {
281 {ACPI_PROCESSOR_DEVICE_HID, },
285 MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);